Lamp guard mounting



June 5, 1956 A. I. APPLETON 2,749,435

LAMP GUARD MOUNTING Filed Aug. 4, 1950 2 Sheets-Sheet 1 $1 IIliIH H/I m? w lgsmlum 22 54 I 35 1 I INVENTOR.

(lrthur 1. @gJZeton June 5, 1956 A. l. APPLETON LAMP GUARD MOUNTING 2 Sheets-Sheet 2 Filed Aug. 4, 1950 .m w M mm,

m a BM mwmm ||||||w ILULH States Patent I fiice 2,749,435 Patented June 5, 1956 LAMP GUARD MOUNTING Arthur I. Appleton, Northbrook, Ill.

Application August 4, 1950, Serial No. 177,753

7 Claims. (Cl. 240-102) The present invention relates generally to electrical lighting units and more specifically to a novel and improved lamp guard mounting having particular utility in electric light fixtures of both the permanently installed and the portable type.

One object of the invention is to provide a lamp guard mounting of extremely simple construction, permitting the guard to be installed or removed with remarkable speed and facility and without the need for tools of any kind.

Another object is to provide a lamp guard mounting adapted to withstand vibration and shock satisfactorily and which will be capable of holding the guard securely in position over a long period of time without the likelihood of becoming corroded or rusted in place.

Another object is to provide a lamp guard mounting of the type set forth and which will permit the guard to be used as a disassembling tool for certain types of lighting fixtures.

Other objects and advantages will become apparent as the following description proceeds, taken in connection with the accompanying drawings, wherein:

Figure 1 shows in elevation a lighting fixture having an illustrative lamp guard embodying the present invention.

Fig. 2 is a fragmentary, exploded view showing portions of the fixture and lamp guard illustrated in Fig. 1.

Fig. 3 is a broken sectional view through a portion of the fixture of Fig. 1, such view being taken in the plane of the line 33 in Fig. 2.

Fig. 4 is a plan view taken from one end of the lamp guard, in the plane of the line 44 in Fig. 2.

Fig. 5 is a fragmentary sectional view taken through a portion of the illustrative lamp guard mounting, in the plane of the line 5-5 in Fig. 6.

Fig. 6 is a fragmentary sectional view taken in the plane of the line 6-6 in Fig. 5.

Fig. 7 is an enlarged broken sectional view detailing one of the detent fittings utilized in the illustrative lamp guard mounting of Fig. 1.

Fig. 8 is a fragmentary elevational view showing another lighting fixture and guard equipped with a slightly modified form of lamp guard mounting also embodying the present invention.

Fig. 9 is a fragmentary exploded view showing certain portions of the fixture and lamp guard illustrated in Fig. 8 but in disassembled relation with respect to each other.

Fig. 10 is a broken sectional view detailing certain elements of the mounting, such view being taken in the plane of the line 1010 in Fig. 9.

Fig. 11 is a plan view taken in the plane of the line 11-11 in Fig. 9 and showing one end of the lamp guard.

Fig. 12 is an enlarged, fragmentary transverse sectional view taken through Fig. 13 and in the plane of the line 12-42.

Fig. 13 is an enlarged fragmentary sectional view taken along the surface of the fixture member in the plane of the arc l3-13 in Fig. 12.

Fig. 14 is an enlarged broken sectional view detailing I one of the detent fittings utilized in the modified lamp guard mounting.

While the invention is susceptible of various modifications and alternative constructions, certain preferred embodiments have been shown in the drawings and will be described below in considerable detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Upon more specific reference to Fig. 1, it will be noted that there is shown an electrical lighting fixture 20 which happens to be of the vapor-proof type. The fixture 20 comprises a supporting canopy 21, a globe ring or adapter 22, and an inverted, dome-shaped globe 24 of glass or the like. The globe 24 is protectively enclosed within a cage-like lamp guard 25, the latter being secured to the fixture 20 by means of an illustrative mounting 26 embodying the present invention. The fixture canopy in this instance is fashioned with a peripheral groove 28 which facilitates attachment of a reflector, should one be desired.

Turning now to the guard mounting 26 per se, it will be noted that the same comprises an annular collar 29 which in this instance is integral with globe ring 22. The collar 29 has a relatively smooth cylindrical surface terminating in a peripheral shoulder 30 which serves as a seating abutment for the guard 25. By the same token, the guard 25 is formed with an annular collar 31 adapted to telescope over the collar 29 with a comfortable sliding fit, the end of the collar 31 abutting snugly against the shoulder 30.

Provision is made for permitting attachment of the lamp guard 25 to the globe ring 22 by the simple expedient of telescoping the collar 31 of the lamp guard over globe ring collar 29 and imparting a moderate circum ferential twist to the lamp guard. In furtherance of such objective, the collar 29 is fashioned with one or more generally L-shaped recesses 32 in its cylindrical surface. Each of the recesses 32 has an axially extending portion including a side wall 33 and a somewhat longer circum-- ferentially extending portion including a side wall 34 lo cated adjacent the depending end of the collar 29. The side wall 34 is skewed relative to the axis of the collar and defines a ramp disposed at an acute angle to the.- plane of the shoulder abutment 30. By the same t0ken,, the collar 31 of the lamp guard is equipped with one or more lug fittings 35 (Figs. 2, 5 and 7) corresponding in number to the recesses 32. As detailed in Fig. 7, each of the fittings 35 in the present instance comprises a threaded body 36 terminating at one end in a polygonal, nut-like head 38 and at its opposite end in a smooth cir'-- cular boss 39 having a diameter slightly less than that of the body. 36. The fitting 35 is threadedly secured in a. tapped radial hole in the lamp guard collar 31 with its: boss 39 projecting within the inner peripheral surfaceof the collar. Each of the fittings 35 is so located on the lamp guard collar 31 that when the latter telescopes over the globe ring collar 29, the boss 39 will enter the axially extending portion of the recess 32, and, upon circumferential movement of the guard to the right (as. viewed in Figs. 1, 2 and 6), will carn against the ramp 34 of the recess. Due to the fact that the boss 39 has a diameter somewhat smaller than the width of the axially extending portion of the recess 32, this camming action: between the boss and the ramp urges the end of the lamp guard collar 31 into snug frictional engagement with the shoulder 30.

Provision is also made for maintaining the collar 31 in tight frictional engagement with the shoulder 35 by means which will produce sufficient resistance to preclude disengagement of the guard 25 from the globe ring 22 without the application of a deliberate loosening torque to the guard. Preferably, this is accomplished by incorporating a spring loaded detent 40 into each of the lug fittings 35 and by contouring the floor of each recess 32 in an appropriate manner to cooperate with such detent. Accordingly, each of the fittings 35 is fashioned with a relatively large axial bore 41 housing a compression spring 42 and a hardened ball 44, such parts being retained within the bore 4-2 as by swaging its end portion inwardly. To cooperatively receive the detent 4% of the lug fitting associated therewith, each of the recesses 32 has a latching notch 45 in the floor of its circumfercntially extending portion. The notch 45 is so located and dimens oned that the spring loaded ball 44 will enter it just as the boss 39 begins to cam up the ramp 34 to initiate snug frictional engagement between the lamp guard collar 31 and the shoulder 30. By reason of the foregoing construction, the torque which must be applied to the guard 25 to loosen the same is determined to a large extent by the stiifness and loading of the detent spring 4?; in each fitting 35. By maintaining these factors sufficiently high, inadvertent disengagement of the guard due to vibration and shock is virtually precluded.

To allow for the possibility that an installer might not turn the guard 25 sufficiently far to engage the detent balls 4 with their respective latching notches 45, an important safety feature is included. This involves the provision of a safety notch 46, which may be circular, in the fioor of the axially extending portion of each recess 32. As will readily be appreciated, the notch 46 simply defines another stopping point for the detent 49. Thus in the event of incomplete engagement between the ball 44 and its associated notch 45 and resulting vibrational movement tending to turn the lamp guard to the left, the ball 44 will automatically enter the recess 4-6 and arrest the lamp guard 25 before the latter can drop away from the collar 29.

The foregoing feature also facilitates the utilization of the lamp guard 25 as a tool for disassembling the fixture 20. For example, in the event that the globe ring 22 should be threaded into the canopy 21, the globe ring may easily be unscrewed by twisting the lamp guard from its fully engaged position until the detent ball 44 enters the notch 46. boss 39 will abut hard against the side wall 33 of the axially extending portion of the recess 32. Consequently, further twisting movement of the lamp guard, which can be easily clone by hand, results in unscrewing the globe ring 22 from the canopy.

Turning now to Figs. 8 to 14, there is shown fragmentarily a fixture closely similar to the fixture but equipped with a modified lamp guard mounting 26A for securing the guard to the collar 29 of the globe ring. As indicated more particularly in Figs. 9 and 13, the collar 2? is provided with one or more recesses 32A similar to the recesses 32 already described and each having a ramp-like side wall 34. In lieu of the lug fitting 35, the lamp guard collar is provided with a roller 48 comparable in size to the boss 39 but journaled upon radial stud 49 fired to the collar 3* (See Figs. 12 and 13.) With the foregoing structural arrangement, the end of the lamp guard collar 31 will be cammed into frictional engagement with the shoulder by pressure arising from contact of the roller 48 with the inclined ramp 34.

In the modified lamp guard mounting 26A, provision is made for positively retaining the guard 25 in assembled position on the collar of the globe ring 22. This is accomplished by the use of a spring loaded detent 50 (Figs. 12 and 14) separate from the stud and roller 48, 49 and With the members in this position, the

comprising a threaded fitting 51 susceptible of mounting in a tapped hole running radially of the collar 31 in the lamp guard. The fitting 51 is fashioned with an axial bore 52 and counterbore which house a sliding plunger 53, together with a loading spring 54. These parts are prevented from leaving the bore 52 by means of a concave flange 55 integrally fixed to the upper end of the plunger 53. To receive the inner end of the plunger 53 when the lamp guard 31 is telescoped over the globe ring collar 29, the latter is provided with one or more recesses 56 corresponding in number to that of the detents 50. Each of the recesses 56 has the general shape of the recess 32A but has an entirely dilferent lloor contour. As illustrated in Figs. 12 and 13, the left-hand portion 58 of each recess 56 has a relatively large depth which is sufiicient to accommodate the plunger 53 without compression of its loading spring 54 when the lamp guard is moved axially of the collar 29 in the initial stages of installation. The depth of the portion 58 de creases in a circumferential direction, reaching a high point 59 substantially even with the outer peripheral surface of the collar 29. Continuing in the same circumferential direction, the recess floor again tapers downwardly to define a series of arcuate steps 60 of segmental shape, with the exception of the last step which is substantially circular. It can now be appreciated that as the lamp guard collar 31 is telescoped over the globe ring collar 29 and twisted to the left, as viewed in the drawings, the plunger 53 will automatically become cocked by the upwardly inclining portion 58 of the recess floor. Shortly before snug frictional engagement occurs between the end of the collar 31 and the shoulder St) on the globe ring, the plunger 53 will cam over the high spot 59 in the recess floor and thereupon drop down onto successive ones of the steps 60. This arrangement positively precludes reverse turning of the lamp guard 25 and securely locks the same in place on the collar 29. The guard may, however, readily be removed by the simple act of grasping each detent collar 55 with the fingers and pulling the same radially outward so that the inner end of the plunger 53 will clear the steps 69 and the high spot 59 in the recess floor. Disengagement of the guard may then occur without difiiculty by means of a slight additional twist followed by an axial withdrawing movement.

The modified lamp guard mounting 26A is susceptible of use on permanently installed fixtures as well as portable ones. However, it finds particular utility in devices such as hand lamps where the guard is subjected to considerable abuse and shock which might be sufficient to loosen a guard mounting such as the mounting 26 already described above.

It will now be apparent to those skilled in the art that the lamp guard mountings disclosed herein have a self-compensating characteristic as far as wear is concerned. This is due to the fact that each such mounting enables the guard to be secured in place over a relatively wide range of circumferential displacement, the exact point of engagement being determined by the Wear of the parts. Since the rate at which such parts will wear is rather slight, there is little if any likelihood that either the mounting 26 or the mounting 26A will need replacement during the life of the fixture with which it may be used.

I claim as my invention:

1. A lamp guard mounting comprising, in combination, a first collar adapted for fixed attachment upon a lighting fixture, a second collar integral with a lamp guard and telescopically related to said first collar, one of said collars having a stop abutment thereon and a generally L-shaped recess therein, one of the side walls of said recess being skewed relative to the plane of said stop abutment, the other of said collars having a radially extending cam abutment adapted to enter the L-shaped recess and cam against the skewed side wall thereof to bring said other collar against said stop abutment when said collars are telescoped together, a radially extending spring loaded detent on one of said collars, the other of said collars having a Wear compensating detent notch of graduated radial depth therein, said detent and said notch being adapted to resist separation of said cam abutment and said skewed side wall and hence resist separation of said other collar and said stop abutment.

2. A lamp guard mounting comprising the combination of a first collar having a peripheral abutment thereon, a second collar telescopically related to said first collar, means including a radially extending cam abutment on one of said collars and a circumferentially extending ramp on the other of said collars for urging said second collar into frictional engagement with said peripheral abutment, and a radially extending spring loaded detent interposed between said collars, said detent being carried by said cam abutment and adapted to resist disengagement between said cam abutment and said ramp, one of said collars having a radial safety notch for effecting initial engagement with said detent and also having a radial latching notch for effecting final engagement with said detent.

3. A lamp guard mounting comprising the combination of a first collar and a second collar adapted to telescope thereover, said first collar having a peripheral abutment adapted to serve as a seat for said second collar, means defining an inclined ramp in one of said collars, a cam abutment on the other of said collars engageable with said ramp, a spring loaded detent carried by one of said collars, said detent being manually releasable, and means defining in the other of said collars a series of arcuate steps positively engageable by said detent.

4. A lamp guard mounting for an electrical lighting fixture and comprising, in combination, a first collar rigidly supportable upon the fixture, a second collar rigidly fixed to a lamp guard and telescopically related to said first collar, one of said collars having a generally L-shaped recess therein with a portion running axially and another portion running circumferentially of said one collar, the floor of said recess having a detent notch in said axially extending portion and a second detent notch in said circumferentially extending portion, a generally radially extending boss on the other of said collars, said boss being of appropriate size to enter both the axially and circumferentially ex tending portions of said recess, and a spring loaded detent housed within said boss, said detent being susceptible of engaging the notches in said recess floor to yieldably resist withdrawal of said boss from both the circumferentially and the axially extending portions of said recess.

5. A lamp guard mounting for an electrical lighting fixture and comprising the combination of a first collar rigidly supportable upon the fixture, a second collar rigidly fixed to a lamp guard and telescopically related to said first collar, means for releasably securing said collars together by relative circumferential movement in a given direction but less than one revolution, one of said collars having a recess running generally circumferentially thereof, the floor of said recess being tapered in said given circumferential direction upwardly to a high point and thence downwardly in a series of radial steps, and a spring loaded detent plunger mounted on the other of said collars, said plunger being susceptible of interception by various ones of said series of radial steps to preclude relative circumferential movement between said collars in the opposite direction.

6. A lamp guard mounting for an electrical lighting fixture and comprising, in combination, a first collar and a second collar adapted to fit together telescopically, one of said collars having a peripheral abutment adapted to serve as a seating surface for the end of said other collar, one of said collars having a generally L-shaped recess therein defining a ramp inclined to the plane of said peripheral abutment, the other of said collars having a roller journaled thereon, said roller being of appropriate size to enter said L-shaped recess and traverse said inclined ramp so as to cam said collars into frictional engagement, one of said collars having another substantially L-shaped recess with a series of positive steps in the floor thereof extending in the same circumferential direction as said first recess, the other of said collars having a spring loaded plunger susceptible of engaging various ones of said series of steps to preclude descent of said roller along said inclined ramp, and a handle rigidly fixed to said detent plunger for cocking the same manually to clear said steps, said handle being accessible from the exterior of the lighting fixture.

7. A lamp guard mounting comprising the combination of a first collar adapted for fixed attachment upon a lamp fixture, a second collar fixed to a lamp guard and having a telescoping fit with said first collar, one of said collars having a generally L-shaped recess therein extending axially and circumferentially thereof, said recess having a safety notch of radial depth in the axially extending portion of said recess and a latching notch of radial depth in the circumferentially extending portion of said recess and spaced circumferentially from said safety notch, and a radially extending spring loaded detent carried by the other of said collars, said detent being engageable with the safety notch when said collars are initially brought together, said detent also being engageable with the latching notch after said collars have been brought together and moved circumferentially relative to each other.

References Cited in the file of this patent UNITED STATES PATENTS Re. 17,979 Wolarsky Feb. 24, 1931 987,744 Rennert Mar. 28, 1911 1,448,345 Hawkins Mar. 18, 1923 1,460,394 Tweedy July 3, 1923 1,728,302 Namet et a1 Sept. 17, 1929 1,762,724 Manneschrnidt June 30, 1930 1,910,542 Hendee May 23, 1933 2,592,208 Stamper Apr. 8, 1952 FOREIGN PATENTS 253,038 Great Britain June 10, 1926 

